Crane mat and method of manufacture

ABSTRACT

A crane mat is disclosed having a plurality of panels of lumber positioned in alternating transverse directions with respect to one another, where the top and bottom panels are oriented parallel to the direction of vehicular traffic. The top and bottom panels may include a plurality of spaced apart grooves extending longitudinally from a first longitudinal end of the crane mat to a second longitudinal end of the crane mat for enhancing traction of a vehicle when traversing across the crane mat by transporting rain or moisture off the mat, or for receiving mud or other debris. The crane mat may include a plurality of edge protectors positioned on respective sides of the crane mat to protect the crane mat from handling damage. In various embodiments, the crane mat may be manufactured using either softwood, hardwood, or any combination of softwood and hardwood.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of U.S. Nonprovisionalapplication Ser. No. 14/932,329, filed Nov. 4, 2015, which claims thebenefit of U.S. Provisional Application No. 62/200,508, filed Aug. 3,2015, and U.S. Provisional Application No. 62/211,651, filed Aug. 28,2015. All of these applications are incorporated by reference herein intheir entirety.

BACKGROUND

This application relates generally to the field of temporary roadwaysand/or ground protection, and more particularly to crane mats andmethods and systems for their manufacture.

SUMMARY

An embodiment of a crane mat is disclosed comprising a plurality ofpanels positioned in alternating transverse directions with respect toone another. Each of the panels is laminated to an adjacent one of thepanels, and each of the panels comprise a plurality of lumber memberspositioned sided by side. The plurality of lumber members of each panelare oriented in either a longitudinal direction or a transversedirection of the crane mat. The plurality of lumber members in a toppanel and a bottom panel of the crane mat are oriented in the transversedirection, which is parallel to a direction of travel of vehiculartraffic thereon. In some embodiments, the top and bottom panels includea plurality of spaced apart grooves extending longitudinally from afirst longitudinal end of the crane mat to a second longitudinal end ofthe crane mat for enhancing traction of a vehicle when traversing acrossthe crane mat. The plurality of grooves are positioned longitudinallyalong a portion of the top and bottom panels of the crane mat. In someembodiments, the crane mat includes an edge protector removablypositioned along at least a portion of respective longitudinal sides ofthe crane mat. The edge protector includes a U-shaped cross section anda plurality of longitudinal protrusions engaging a plurality of groovesin the top and bottom panels.

The plurality of panels may include a softwood species, a hardwoodspecies, or any combination of the softwood and the hardwood species. Atleast one of the plurality of lumber members in the top and bottompanels may include a hardwood species. At least one of the plurality oflumber members in at least one of the panels positioned between the topand bottom panels may include a softwood species. The hardwood speciesmay include at least one of oak, maple, hickory, hackberry, and cherry,and the softwood species may include at least one of spruce, pine, fir,southern yellow pine, and hemlock.

The plurality of lumber members in at least one of the panels mayinclude a plurality of different widths of lumber positionedside-by-side. At least one of the plurality of lumber members mayinclude a plurality of wooden members fingerjointed together.

The spaced apart grooves in the top and bottom panels may comprise adepth up to at least approximately one half of a thickness of arespective one of the top and bottom panel. The depth of the spacedapart grooves may vary from the first longitudinal end of the crane matto the second longitudinal end of the crane mat. At least one of thespaced apart grooves comprises a depth that may vary from the firstlongitudinal end of the crane mat to the second longitudinal end of thecrane mat.

The edge protector may include a plastic. The edge protector may includea chamfer positioned along top and bottom longitudinal edges. Each ofthe longitudinal protrusions of the edge protector may include atrapezoidal cross section to ease installation and removal of the edgeprotector on the top and bottom panels of the crane mat.

Another embodiment of a crane mat having a longitudinal length isdisclosed, including: (a) a first panel comprising a plurality of lumberpositioned side by side, the plurality of lumber oriented transverse tothe longitudinal length of the crane mat, (b) a second panel positionedon top of the first panel, the second panel comprising a plurality oflumber positioned side by side and transverse to the plurality of lumberof the first panel, the second panel being glued to the first panel, (c)a third panel positioned on top of the second panel, the third panelcomprising a plurality of lumber positioned side by side and transverseto the plurality of lumber of the second panel, the third panel beingglued to the second panel, (d) a fourth panel positioned on top of thethird panel, the fourth panel comprising a plurality of lumberpositioned side by side and transverse to the plurality of lumber of thethird panel, the fourth panel being glued to the third panel, and (e) afifth panel positioned on top of the fourth panel, the fifth panelcomprising a plurality of lumber positioned side by side and transverseto the plurality of lumber of the fourth panel, the fifth panel beingglued to the fourth panel.

Another embodiment of a crane mat having a longitudinal length isdisclosed, including: (a) a first panel comprising a plurality of lumberpositioned side by side, the plurality of lumber oriented transverse tothe longitudinal length of the crane mat, (b) a second panel positionedon top of the first panel, the second panel comprising a plurality oflumber positioned side by side and transverse to the plurality of lumberof the first panel, the second panel being glued to the first panel, (c)a third panel positioned on top of the second panel, the third panelcomprising a plurality of lumber positioned side by side and transverseto the plurality of lumber of the second panel, the third panel beingglued to the second panel, (d) a fourth panel positioned on top of thethird panel, the fourth panel comprising a plurality of lumberpositioned side by side and transverse to the plurality of lumber of thethird panel, the fourth panel being glued to the third panel, and (e) afifth panel positioned on top of the fourth panel, the fifth panelcomprising a plurality of lumber positioned side by side and transverseto the plurality of lumber of the fourth panel, the fifth panel beingglued to the fourth panel. In this embodiment, the first and fifthpanels include a plurality of spaced apart grooves extendinglongitudinally from a first longitudinal end of the crane mat to asecond longitudinal end of the crane mat for transporting rain ormoisture, or for receiving mud or other debris therein.

Another embodiment of a crane mat having a longitudinal length isdisclosed, including: (a) a first panel comprising a plurality of lumberpositioned side by side, the plurality of lumber oriented transverse tothe longitudinal length of the crane mat, (b) a second panel positionedon top of the first panel, the second panel comprising a plurality oflumber positioned side by side and transverse to the plurality of lumberof the first panel, the second panel being glued to the first panel; (c)a third panel positioned on top of the second panel, the third panelcomprising a plurality of lumber positioned side by side and transverseto the plurality of lumber of the second panel, the third panel beingglued to the second panel; (d) a fourth panel positioned on top of thethird panel, the fourth panel comprising a plurality of lumberpositioned side by side and transverse to the plurality of lumber of thethird panel, the fourth panel being glued to the third panel; (e) afifth panel positioned on top of the fourth panel, the fifth panelcomprising a plurality of lumber positioned side by side and transverseto the plurality of lumber of the fourth panel, the fifth panel beingglued to the fourth panel, and (f) an edge protector removablypositioned along respective longitudinal sides of the crane mat, theedge protector comprising a U-shaped cross section and a plurality oflongitudinal protrusions engaging a plurality of grooves in the firstand fifth panels, the plurality of grooves positioned along a portion ofrespective longitudinal sides of the first and fifth panels.

Another embodiment of a crane mat having a longitudinal length isdisclosed, including: (a) a first panel comprising a plurality of lumberpositioned side by side, the plurality of lumber oriented transverse tothe longitudinal length of the crane mat, (b) a second panel positionedon top of the first panel, the second panel comprising a plurality oflumber positioned side by side and transverse to the plurality of lumberof the first panel, the second panel being glued to the first panel, (c)a third panel positioned on top of the second panel, the third panelcomprising a plurality of lumber positioned side by side and transverseto the plurality of lumber of the second panel, the third panel beingglued to the second panel, (d) a fourth panel positioned on top of thethird panel, the fourth panel comprising a plurality of lumberpositioned side by side and transverse to the plurality of lumber of thethird panel, the fourth panel being glued to the third panel, and (e) afifth panel positioned on top of the fourth panel, the fifth panelcomprising a plurality of lumber positioned side by side and transverseto the plurality of lumber of the fourth panel, the fifth panel beingglued to the fourth panel. In this embodiment, the first, second, third,fourth, and fifth panels comprise softwood, hardwood, or any combinationof softwood and hardwood species.

Other embodiments of a crane mat, and variations thereto, are disclosedherein. All of the embodiments of a crane mat disclosed herein may bepositioned on the ground for use in the creation of a temporary roadwayor platform for vehicles, cranes, construction equipment, and othermobile or stationary machinery. To accommodate relatively wide widths ofcranes or other vehicles, crane mats of the instant disclosure areconfigured for placement on the ground with the long side of each cranemat positioned transverse to the direction of travel of the crane orvehicle thereon. Additional crane mats of the instant disclosure may bepositioned in the same orientation with respect to one another, withrespective long sides of adjacent crane mats lying adjacent to oneanother. Crane mats of the instant disclosure may be combined with othermats of different configurations to account for variations in thestability of the ground. For example, crane mats of the instantdisclosure may be positioned across timber mats to account forrelatively unstable terrain.

An offset pattern can also be created in the field where crane mats ofthe instant disclosure are all oriented in the same direction but arepositioned in a laterally overlapping manner with longitudinal ends ofadjacent crane mats positioned offset to one another. The relativelyshorter side of the crane mats of the instant disclosure being orientedin the direction of travel of the crane or vehicle best approximates thecontour of the ground. As a result, tilting or other undesired movementof each crane mat will be minimized as a crane, for example, travelsover a temporary roadway formed from a plurality of crane mats of theinstant disclosure. Positioning successive crane mats on the ground withthe long sides of each mat positioned adjacent one another and the shortsides of each mat oriented in the direction of travel makes it easy fora forklift or crane to quickly install each crane mat sequentially infront of one another by using the prior laid crane mat as the roadway orsupport for the traversing forklift or crane to enable the forklift orcrane to position the next one in line. Crane mats positioned in thisorientation on the ground allows for the safe and comfortable passage ofcranes and other vehicles on undeveloped ground.

By contrast, orienting multiple crane mats of the instant disclosureside by side to obtain the necessary width to accommodate wide vehicleswhile orienting the long side of the crane mats in the direction oftravel would lead to undesirable tilting, deflection and/or movement ofthe crane mats as the crane or vehicle travels over the temporaryroadway, particularly on ground that slopes upwardly or downwardly inthe direction of travel. This orientation will not allow for the safeand comfortable passage of cranes and other vehicles across undevelopedground.

A method of making a crane mat comprising a length that is longer than awidth is disclosed, comprising: (a) vacuum lifting and positioning on anautomatically vertically indexing table a first panel to receive aplurality of panels thereon, the first panel comprising a plurality offirst lumber members positioned side-by-side, each of the plurality offirst lumber members being oriented in a first direction that isparallel to the width, (b) dispensing an adhesive on a top surface ofthe first panel, (c) vertically positioning the indexing table toreceive a second panel, (d) vacuum lifting and positioning the secondpanel on the top surface of the first panel, the second panel comprisinga plurality of second lumber members positioned side-by-side, each ofthe plurality of second lumber members being oriented in a seconddirection that is parallel to the length, (f) dispensing an adhesive ona top surface of the second panel, (g) vertically positioning theindexing table to receive a third panel, (h) vacuum lifting andpositioning the third panel on the top surface of the second panel, thethird panel comprising a plurality of third lumber members positionedside-by-side, each of the plurality of third lumber members beingoriented in the first direction, (i) dispensing an adhesive on a topsurface of the third panel, (j) vertically positioning the indexingtable to receive a fourth panel, (k) vacuum lifting and positioning thefourth panel on the top surface of the third panel, the fourth panelcomprising a plurality of fourth lumber members positioned side-by-side,each of the plurality of fourth lumber members being oriented in thesecond direction, (l) dispensing an adhesive on a top surface of thefourth panel, (m) vertically positioning the indexing table to receive afifth panel, (n) vacuum lifting and positioning the fifth panel on thetop surface of the fourth panel, the fifth panel comprising a pluralityof fifth lumber members positioned side-by-side, each of the pluralityof fifth lumber members being oriented in the first direction, (o)applying a compressive force to the first, second, third, fourth andfifth panels as a unit until the adhesive is set, and (p) cutting theunit to desired peripheral dimensions.

The method may include the step of vacuum lifting and positioning adivider panel on the indexing table before step (a). The divider panelmay be made from a plastic, such as high density polyethylene (HDPE),which impedes the adhesive from sticking to the divider panel. Themethod may include the step of vacuum lifting and positioning a dividerpanel on the indexing table after step (n). The method may includerepeating steps (a) through (o) at least four times to form a stack ofat least five units, wherein each of the units is separated by a dividerpanel, and applying the compressive force to the stack of at least fiveunits until the adhesive is set. The method may include the step ofde-stacking the units before cutting. De-stacking may be performed usinga vacuum lift system.

The step of applying a compressive force to the unit may includeapplying pressure for approximately 25 minutes. The first and the fifthpanels may include hardwood lumber and the second, the third, and thefourth panels may include softwood lumber.

The method may include the step of planing a top and a bottom face ofeach of the first, the second, the third, the fourth, and the fifthlumber members before initiating step (a). The method may include thestep of forming the first panel, the second panel, the third panel, thefourth panel, and the fifth panel by positioning the respectiveplurality of first, second, third, fourth, and fifth lumber membersside-by-side.

A high speed manufacturing system for making a crane mat is disclosed,comprising a layer assembler that positions lumber members horizontallyside-by-side to form a lumber layer of a desired peripheral size, arobotic assembler comprising (a) a vacuum lifter to lift and positionthe lumber layer onto an indexer table, wherein the indexer tableautomatically adjusts a height of the table to receive the lumber layerand a plurality of next lumber layers positioned in sequence verticallythereon and transverse to one another, and (b) an adhesive dispenser todispense adhesive across each lumber layer, a press to compress at leastfive lumber layers together as an assembled unit to bond the layers bythe adhesive, and a plurality of saws to cut the bonded layers to afinished size while the assembled unit is conveyed past the saws.

The lumber members in respective top and bottom panels may include ahardwood species, and the lumber members in each of the panelspositioned between the top and bottom panels may include a softwoodspecies. The press may be one of a plurality of laterally movablepresses configured to receive the unit from the robotic assembler.

The system may include a conveyor to continuously convey lumber. Thesystem may include a planer connected to the conveyor to plane thelumber prior to forming the lumber layer. The system may include aprimer connected to the conveyor to prime the lumber after planing butprior to forming the lumber layer. The system may include a computercontroller comprising a computer processor, a computer readable mediumaccessible by the processor, and software stored on the computerreadable medium for executing the step of controlling the conveyor, theplaner, the primer, the robotic assembler, the adhesive dispenser, thepress, and the saws.

The press may be configured to apply a compressive force simultaneouslyto at least 5 assembled units mounted on top of one another. The systemmay include a layer trimmer configured to trim each of a plurality oflongitudinal ends of the lumber members positioned side-by-side toadjust a length of the lumber members to form the lumber layer.

A method of making a crane mat is disclosed, comprising: (1) positioninga plurality of lumber members side by side to form a plurality ofpanels, (2) positioning a plurality of panels on one another inalternating transverse directions with respect to one another, where theplurality of lumber members in a top panel and a bottom panel areoriented in a transverse direction, and where the plurality of lumbermembers in at least one panel positioned between the top panel and thebottom panel is oriented in a longitudinal direction, and (3) bondingeach of the panels to an adjacent one of the panels with an adhesive.

The plurality of lumber members in the top and bottom panels may includea hardwood species, and the plurality of lumber members in the panelspositioned between the top and bottom panels may include a softwoodspecies.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates one embodiment of a crane mat of the instantdisclosure.

FIG. 1B illustrates a side end view of the embodiment shown in FIG. 1A.

FIG. 10 illustrates another embodiment of a crane mat of the instantdisclosure.

FIG. 1D illustrates a side end view of the embodiment shown in FIG. 10.

FIG. 1E illustrates another embodiment of a crane mat of the instantdisclosure.

FIG. 1F illustrates a side end view of the embodiment shown in FIG. 1E.

FIG. 2A illustrates another embodiment of a crane mat of the instantdisclosure.

FIG. 2B illustrates a side end view of the embodiment shown in FIG. 2A.

FIG. 3A illustrates a partial exploded view of another embodiment of acrane mat of the instant disclosure.

FIG. 3B illustrates an unexploded view of the embodiment shown in FIG.3A.

FIG. 3C illustrates a cross sectional view of the embodiment shown inFIG. 3B.

FIGS. 4A and 4B illustrate a block diagram of a method of manufacturingone embodiment of a crane mat of the instant disclosure.

FIGS. 5A-1 through 5A-8 illustrate a block diagram of a method ofmanufacturing at least one embodiment of a crane mat of the instantdisclosure.

DETAILED DESCRIPTION

Although the figures and the instant disclosure describe one or moreembodiments of a crane mat, one of ordinary skill in the art wouldappreciate that the teachings of the instant disclosure would not belimited to these embodiments. For example, the instant disclosure canalso apply to access mats and other temporary roadway or groundprotection devices.

Turning now to the drawings wherein like reference numerals refer tolike elements, FIGS. 1A-1F, 2A-2B, 3A-3C, and 4A-4B illustrate exemplaryembodiments and methods of manufacture of a crane mat comprising aplurality of panels for use in the creation of a temporary roadway orplatform for vehicles, cranes, construction equipment, and other mobileor stationary machinery.

As shown in the embodiment of FIGS. 1A-1B, crane mat 100 includes panels102, 104, 106, 108, 110. In other embodiments, crane mat 100 may beconfigured with any number of panels from a minimum of one panel to amaximum of thirteen panels to provide a desired strength and/oroperating performance. In this embodiment, panel 102 is positioned ontop of panel 104, which is positioned on top of panel 106, which ispositioned on top of panel 108, which is positioned on top of panel 110.In other embodiments, panel 110 may be positioned on top of panel 108,which may be positioned on top of panel 106, which may be positioned ontop of panel 104, which may be positioned on top of panel 102. In use,crane mat 100 may be fully reversible, with either of panels 102 or 110acting as the working surface for receiving vehicles, cranes,construction equipment or other mobile or stationary machinery, and withthe other of panels 102 or 110 being configured for placement on, forexample, the ground, a roadway, a ramp, a platform or other crane mat orobject.

In this embodiment, panel 102 is glued to panel 104, panel 104 is gluedto panel 106, panel 106 is glued to panel 108, and panel 108 is glued topanel 110. In other embodiments, panels 102, 104, 106, 108, and 110 areconnected to one another using bolts, screws, straps, clips, or otherfastening or joining techniques or any combination of them. In thisembodiment, each of panels 102, 106, 110 is oriented in a firstdirection and panels 104, 108 are oriented in a second directionapproximately 90 degrees relative to panels 102, 106, 110. In otherembodiments, panels 102, 104, 106, 108, and 110 may be oriented at anyangle relative to one another, including all panels lying in the samedirection, to provide a desired strength and/or operating performance ofcrane mat 100. In one embodiment, at least two adjacent panels of thecrane mat are aligned in approximately the same direction (see, e.g.,FIGS. 1C-1F). The overall strength and rigidity of crane mat 100 islikely maximized, however, by alternating the direction of respectiveadjacent panel layers.

In this embodiment, each of panels 102, 106, 110 includes a plurality ofmembers 112 positioned side-by-side along respective side ends 115. Eachmember 112, and particularly each side end 115 of each member 112, isoriented in the first direction. For purposes of this disclosure, thefirst direction is oriented parallel to the general direction of travelof vehicular traffic on crane mat 100. As shown in FIGS. 1A-1B, thelength “L1” of each member 112 is longer than a width “W1” of eachmember 112, and the width of each member 112 is longer than a depth orheight “H1” of each member 112. Although members 112 are shown in thefigures as being of the same length “L1,” in other embodiments, for eachmember 112, the length “L1” thereof may comprise a plurality of separatemembers that together result in achieving the length “L1” for eachmember 112. In addition, it should be understood that the combination ofmembers that form each member 112 may vary in length from one toanother. Such combination of members forming each member 112 in suchother embodiments may be spliced or joined together using any number oftechniques, including fingerjointing, lap jointing, rabbit jointing,tongue and groove jointing, miter joining and the like, or they maysimply be positioned adjacent one another to form a butt joint. In thisway, pieces of lumber having differing lengths can be pieced together toform each member 112.

In this embodiment, each of panels 104, 108 includes a plurality ofmembers 114 positioned side-by-side along respective side ends 117. Eachmember 114, and particularly each side end 117 of each member 114, isoriented in the second direction. As shown in FIGS. 1A-1B, the length“L2” of each member 114 is longer than a width “W2” of each member 114,and the width of each member 114 is longer than a depth or height “H2”of each member 114. Consequently, in this embodiment, the length of eachmember 114 of each of panels 104, 108 is oriented in the seconddirection, which is 90 degrees relative to the first direction andtransverse to the general direction of travel of vehicular traffic oncrane mat 100. In addition, as shown in FIGS. 1A-1B, in this embodiment,the length of members 114 is greater than the length of members 112,whereas the width and height of members 114 and members 112 areapproximately the same as one another. Although members 114 are shown inthe figures as being of the same length “L2,” in other embodiments, foreach member 114, the length “L2” thereof may comprise a plurality ofseparate members that together result in achieving the length “L2” foreach member 114. In addition, it should be understood that thecombination of members that form each member 114 may vary in length fromone to another. Such combination of members forming each member 114 insuch other embodiments may be spliced or joined together using anynumber of techniques, including fingerjointing, lap jointing, rabbitjointing, tongue and groove jointing, miter joining and the like, orthey may simply be positioned adjacent one another to form a butt joint.In this way, pieces of lumber having differing lengths can be piecedtogether to form each member 114.

In this embodiment, members 114 are generally aligned in a longitudinaldirection (i.e., the second direction) of crane mat 100, and members 112are generally aligned transverse (i.e., in the first direction) tomembers 114. Thus, in this embodiment, the length of members 114 definesthe longitudinal length of crane mat 100, and the length of members 112defines the transverse width of crane mat 100, where length “L2” islonger than length “L1”. For vehicular traffic moving across crane mat100 in the first direction and transverse to the longitudinal directionof crane mat 100, members 112 of panel 102 (or panel 110 if orientedupside down as compared to the orientation shown in FIGS. 1A-1B) will beoriented to maximize resistance to wear and damage that may be caused byvehicular traffic over crane mat 100, resulting in longer crane mat lifeand reduced costs. In other words, vehicular traffic coming upon cranemat 100 will strike a longitudinal end of various members 112 in panel102 (or panel 110 if oriented upside down) where the end grain of thelumber is exposed. The end grain of members 112 provides superiorresistance to wear and tear from vehicle traffic, and particularly incomparison to vehicle movement in the second, longitudinal direction ofcrane mat 100. In addition, because the majority of the panels in cranemat 100 comprise members 112 having length “L1” that is shorter thanmembers 114 having length “L2”, crane mat 100 may contour to the actualsurface of the ground, and will result in a lower weight crane mat thatreduces shipping costs.

In one embodiment, crane mat 100 is configured to be approximately 4feet wide in the first, transverse direction and 16 feet long in thesecond, longitudinal direction. In another embodiment, crane mat 100 isconfigured to be approximately 4 feet wide in the first, transversedirection and 18 feet long in the second, longitudinal direction. Inanother embodiment, crane mat 100 is configured to be approximately 4feet wide in the first, transverse direction and 20 feet long in thesecond, longitudinal direction. In another embodiment, crane mat 100 isconfigured to be approximately 4 feet wide in the first, transversedirection and 22 feet long in the second, longitudinal direction. In yetanother embodiment, crane mat 100 is configured to be approximately 4feet wide in the first, transverse direction and 24 feet long in thesecond, longitudinal direction. In other embodiments, crane mat 100 mayhave a width that is smaller or larger than 4 feet and a length that isshorter or longer than 16 feet. In use, multiple crane mats 100 may beabutted adjacent one another or attached to one another along the longside of crane mat 100 to orient the short side of crane mat 100 andparticularly members 112 so as to be positioned in the direction ofvehicle movement. In this way, the long side of the crane mat ispositioned to accommodate wide vehicles traveling parallel to theorientation of members 112.

In other embodiments, crane mat 100 is configured to be approximately 8feet wide in the first, transverse direction and either 14, 16, or 18feet long in the second, longitudinal direction. In some embodiments,the top layer and the bottom layer of crane mat 100 may be configuredwith hardwood dimensional lumber that is 8 feet long positionedside-by-side and oriented in the first, transverse direction until thedesired 14, 16, or 18 feet long in the second, longitudinal direction isobtained. Each one of a pair of longitudinally-oriented intermediatelayers comprising softwood dimensional lumber is positioned immediatelyadjacent respective top and bottom hardwood layers. In theseintermediate layers, softwood dimensional lumber that is either 14, 16,or 18 feet long (depending on the desired width of the crane mat) isoriented in the second, longitudinal direction side-by-side until thedesired depth, such as 8 feet, is obtained. For a 5-layer crane mat 100,a third intermediate (middle) layer comprising softwood dimensionallumber is positioned immediately adjacent and between the twolongitudinally-oriented intermediate layers. The third intermediate(middle) layer comprises softwood dimensional lumber that is 8 feet longpositioned side-by-side and oriented in the first, transverse directionuntil the desired 14, 16, or 18 feet long in the second, longitudinaldirection is obtained. The respective layers of crane mat 100 may beglued to one another and pressed together to form a unitary structure.Excess material may be sawed and/or trimmed from all four perimetersides to obtain uniform dimensions from one crane mat 100 to the next.The top and/or bottom perimeter edges of crane mat 100 may include achamfer to minimize damage to crane mat 100 due to loading, handling,and usage in field. A single 8 ft×16 ft or 18 ft 5-layer crane mat 100may be sawn in half to obtain two 4 ft×16 ft or 18 ft 5-layer crane mats100.

In some embodiments, members 112 are glued or otherwise adhered to oneanother along respective side ends 115, and members 114 are glued orotherwise adhered to one another along respective side ends 117. Inother embodiments, members 112 are connected to one another, and members114 are connected to one another, using bolts, screws, straps, clips, orother fastening or joining techniques or any combination of them.

In this embodiment, each of members 112 is approximately the samegeometry as one another in terms of width, depth, and length. In otherembodiments, the width, depth and/or length of members 112 may vary fromone to another but may be machined to form finished panels 102, 106, 110for crane mat 100. In this embodiment, each of members 114 isapproximately the same geometry as one another in terms of width, depth,and length. In some embodiments, the width, depth and/or length ofmembers 114 may vary from one to another but may be machined to formfinished panels 104, 108 for crane mat 100.

In some embodiments, members 112, 114 may include dimensional lumber,including 1×4, 1×6, 1×8, 1×10, 1×12, 2×4, 2×6, 2×8, 2×10, and 2×12. Insome embodiments, for any given panel, members 112, 114 may comprise thesame width of lumber positioned side-by-side to create the panel. Inother embodiments, for any given panel, members 112, 114 may comprisedifferent or variable widths of lumber positioned side-by-side to createthe panel. In yet other embodiments, for any given panel, members 112,114 may comprise any combination of the same and different widths oflumber positioned side-by-side to create the panel. Members 112, 114 ofone or more panels of crane mat 100 may include softwood lumbercomprising, for example, spruce, pine, fir, southern yellow pine, orhemlock, hardwood lumber comprising, for example, oak, maple, hickory,hackberry, or cherry, or any combination of softwood or hardwood. Forany given member 112, 114, a hardwood species, such as oak, may lieadjacent to a different hardwood species, such as hickory, and asoftwood species, such as pine, may lie adjacent to a different softwoodspecies, such as fir. In some embodiments, a hardwood panel comprisingmembers 112 or 114 may comprise hardwood lumber 1 inch thick with lumbercomprising different widths positioned side-by-side. In otherembodiments, a softwood panel comprising members 112 or 114 may comprisesoftwood lumber 2 inches thick with lumber comprising different widthspositioned side-by-side. In some embodiments, a panel made of one ormore hardwood species of lumber may be positioned adjacent above orbelow and glued to a panel made of one or more softwood species oflumber. In other embodiments, members 112, 114 may include any materialin any stock dimension suitable for creating a temporary roadway,including a plastic, a composite, or a metal.

Turning to FIGS. 1C-1D, there is shown another embodiment of crane mat100. In particular, panel 106 is replaced by panel 111 having aplurality of members 114 positioned side-by-side along respective sideends 117. Each member 114 of panel 111 is oriented in a longitudinaldirection (i.e., the second direction) of crane mat 100. However, asshown in FIG. 1D, each of members 114 of panel 111 are positionedlaterally offset in the first direction relative to respective members114 in adjacent panels 104, 108. The offset side ends 117 of members 114of respective panels 104, 111, 108 provide enhanced lateral stiffness ofcrane mat 100 in the first direction while permitting enhancedlongitudinal flexibility in the second direction than the embodiment ofcrane mat 100 shown in FIGS. 1A-1B.

FIGS. 1E-1F show yet another embodiment of crane mat 100. In thisembodiment, panels 106, 108 are replaced in their entirety by panel 111having a plurality of members 114 positioned side-by-side alongrespective side ends 117 to form a four panel embodiment of crane mat100. Like the embodiment shown in FIGS. 1C-1D, each member 114 of panel111 is oriented in a longitudinal direction (i.e., the second direction)of crane mat 100. Similarly, each of members 114 of panel 111 arepositioned laterally offset in the first direction relative torespective members 114 in adjacent panel 104. The offset side ends 117of members 114 of respective panels 104, 111 provide enhanced lateralstiffness of crane mat 100 while permitting enhanced longitudinalflexibility than the embodiment of crane mat 100 shown in FIGS. 1C-1D.In addition, in applications where increased longitudinal flexibility isdesired over the embodiment shown in FIGS. 1C-1D, the embodiment ofFIGS. 1E-1F provides the added benefits of: (1) reduced fabricationcosts due to less material and fewer manufacturing processes needed toproduce crane mat 100; (2) reduced transportation costs due to lighterweight finished product and smaller finished product volume, whichpermits shipping more crane mat units in a single freight transportationcontainer, and (3) easier handling by users due to lighter weight of thefinished product.

Turning to FIGS. 2A-2B, there is shown another embodiment of a cranemat. Crane mat 200 includes all of the same features, characteristics,and variations described above for crane mat 100 with the addition of aplurality of slots or grooves 201 disposed on the top panel 202 and/orbottom panel 210 of crane mat 200 for enhancing vehicle traction whentraversing across crane mat 200 parallel to the orientation of members212. In this embodiment, panels 202, 204, 206, 208, 210 of crane mat 200are identical to panels 102, 104, 106, 108, 110 of crane mat 100 exceptthat panel 202 is shown as including grooves 201 disposed thereon. Insome embodiments, crane mat 100 may include grooves 201 as described inmore detail below.

As best shown in FIG. 2B, grooves 201 may comprise generally verticalopposing sidewalls 205 and a generally horizontal bottom wall 203. Inother embodiments, grooves 201 may comprise a U-shape (with or without arounded bottom wall), a V-shape, a trapezoidal shape, a semi-circularshape, or any other shape or combination thereof that enhances vehicletraction. In this embodiment, crane mat 200 includes 9 slots or grooves201 positioned on top panel 202 (and bottom panel 210 to providereversibility of crane mat 200), though a greater or fewer quantity ofgrooves 201 are possible.

Grooves 201 may comprise any width and any spacing that permits adesired number of grooves 201 to be positioned on panel 202, 210.Grooves 201 may comprise any depth up to at least approximately one halfof the thickness of panel 202. In one embodiment, grooves 201 comprise adepth from about 0.100″ to about 0.75″. In one embodiment, grooves 201comprise a depth of about 0.25″+/−0.150″. In another embodiment, grooves201 comprise a depth of about 0.50″. In another embodiment, grooves 201comprise a depth of about 0.75″. Grooves may vary in depth from one endof crane mat 200 to another end of crane mat to enhance drainage ofwater from crane mat 200. Grooves 201 may also vary in depth from anypoint along crane mat 200 relative to any other point along crane mat200. For example, the depth of grooves 201 may be more shallow in themiddle of crane mat 200 and progressively deeper toward the periphery toenhance drainage of water from crane mat 200.

In this embodiment, grooves 201 are generally aligned in a longitudinaldirection of crane mat 200 and transverse to members 212, which aregenerally aligned transverse to members 214. In this embodiment, thelength of members 214 defines the longitudinal length of crane mat 200,and the length of members 212 define the transverse width of crane mat200. For vehicular traffic moving across crane mat 200 parallel to theorientation of members 212 (i.e., in the first direction) and transverseto the longitudinal direction of crane mat 200, transversely alignedmembers 212 of panel 202 (or panel 210 if grooves 201 are alsopositioned thereon and if panel 210 is oriented upside down as comparedto the orientation shown in FIGS. 2A-2B) will be oriented to maximizeresistance to wear and damage that may be caused by vehicular trafficover crane mat 200 while grooves 201 provide for rain, moisture, mud orother debris to collect therein and drain therefrom to enhance tractionof the vehicle. In other embodiments, grooves 201 may be oriented in anyangle on panel 202 and/or 210. In some embodiments, the angle of grooves201 relative to other grooves 201 form a pattern on panel 202 and/or210.

Turning to FIGS. 3A-3C there is shown another embodiment of a crane mat.Crane mat 300 includes all of the same features, characteristics, andvariations described above for crane mat 100 with the addition of aplurality of slots or grooves 301, 311 disposed on the top panel 302and/or bottom panel 310 of crane mat 300. In this embodiment, panels302, 304, 306, 308, 310 of crane mat 300 are identical to panels 102,104, 106, 108, 110 of crane mat 100 except that panel 302 is shown asincluding grooves 301, 311 disposed thereon. In some embodiments, cranemat 100 may include grooves 301, 311 as described in more detail below.

In this embodiment, grooves 301 are disposed along the first and lastmembers 312 on top panel 302 and/or the first and last members 312 onbottom panel 310 near the periphery of crane mat 300. Grooves 301provide a means for attaching accessories for joining adjacent matstogether and for handling and manipulation of crane mat 300 at, forexample, the job site. Grooves 301 may also provide a means for engagingwith an embodiment of protectors 350 (discussed below) for protecting atleast a portion of a longitudinal end of crane mat 300 during handlingand use. In this embodiment, grooves 301 are shown as extending along aportion of members 312. In other embodiments, grooves 301 may extendfrom one end to the other end of member 312.

In this embodiment, grooves 311 are disposed on top panel 302 and bottompanel 310 longitudinally and transverse to members 312, which aregenerally aligned transverse to members 314, near the periphery of cranemat 300. Grooves 311 extend along a portion of the periphery of cranemat 300 for limiting the longitudinal motion of protectors 350(discussed below) when engaged thereto.

Grooves 311 may comprise generally vertical opposing sidewalls 305 and agenerally horizontal bottom wall 303. In other embodiments, grooves 311may comprise a U-shape (with or without a rounded bottom wall), aV-shape, a trapezoidal shape, a semi-circular shape, or any other shapeor combination thereof that enables engagement with protrusions 355 ofprotectors 350. Grooves 311 may comprise any depth up to approximatelyone half of the thickness of panel 302, 310. In one embodiment, grooves311 comprise a depth from about 0.100″ to about 0.75″. In oneembodiment, grooves 311 comprise a depth of about 0.25″+/−0.150″. Inanother embodiment, grooves 311 comprise a depth of about 0.50″. Inanother embodiment, grooves 311 comprise a depth of about 0.75″.

In this embodiment, crane mat 300 also includes protectors 350 that areremovably positionable along the longitudinal sides of crane mat 300.Protectors 350 are configured for protecting at least a portion of alongitudinal side of crane mat 300 during handling and use. In thisembodiment, crane mat 300 includes two protectors 350. In otherembodiments, crane mat 300 may include a greater or fewer number ofprotectors 350, and crane mat 300 may include a greater or fewer numberof grooves 311. Protectors 350 may include a longitudinal chamfer 360 ofsufficient size along top and bottom outer edges to permit, for example,a forklift operator to easily insert a forklift blade between twoadjacently positioned crane mats 300 having protectors 350 thereon andto separate the two crane mats 300 for subsequent lifting or handlingoperations.

Protectors 350 may comprise a U-shape to mount over at least a portionof a longitudinal side of crane mat 300. In other embodiments,protectors 350 may be configured to mount over at least a portion of atransverse side of crane mat 300. In such embodiments, protectors 350may be configured to engage with grooves 301. In this embodiment,protectors 350 are configured for attachment to crane mat 300 viaprotrusions 355 that are configured to engage with grooves 311. In otherembodiments, protectors 350 are configured for attachment to crane mat300 via an interference fit with crane mat 300.

In this embodiment, protrusions 355 are configured with at least onelongitudinal chamfer 365 to permit relatively easy installation andremoval of protectors 350 from crane mat 300 when, for example, damageto protector 350 occurs necessitating its replacement. In someembodiments, protrusions 355 have a trapezoidal cross sectional shape.

Protectors 350 may be fabricated from any plastic, includingpolyethylene, polypropylene, polystyrene, polyimide, polyvinyl chloride,and polycarbonate. Protectors 350 may be fabricated from any metal,including steel and aluminum. Protectors 350 may be fabricated from anycomposite material, including fiber reinforced plastics and metalcomposites. Protectors 350 may be fabricated from extrusions, injectionmoldings, stampings, laminations, forgings, castings, and the like.

Turning to FIGS. 4A-4B, there is shown one embodiment of a method ofmaking a crane mat of the present disclosure comprising an apparatus orsystem 400. It should be understood that other types of vehicle orground protection mats, including access mats, can be manufactured bysystem 400 using the method disclosed herein. In various embodiments,one or more aspects of system 400 can be merged with one another,omitted, or made part of additional apparatuses or system components.These systems may be configured to fabricate a crane mat billet, whichmay be further cut or trimmed to meet customer specifications.

In various embodiments, a method of making crane mat 100 includes thesteps of (1) receiving lumber of a desired species, cross-sectionaldimensions, and length, (2) planing both faces of the lumber to obtainuniform lumber thickness, and to clean and open up the wood fiber on thesurface to receive primer and adhesive, (3) priming the planed faces topromote improved adhesion by an adhesive, (4) trimming a group of lumberpieces laid face up and side-by-side to desired peripheral dimensions toform a layer, and in the case of hardwood lumber, drying the lumbersurfaces to obtain a desired moisture content of the lumber tocoordinate the properties of the lumber with the properties of thechosen adhesive, (5) assembling a group of layers together by (i)perpendicularly orienting respective adjacent layers with respect to oneanother, (ii) applying adhesive between respective adjacent layers,(iii) applying a compressive force to the assembled layers for a desiredperiod of time to set the adhesive, and (6) cutting the assembled layersto desired dimensions. In some embodiments, multiple 5-layer crane mats100 are stacked together during the step of applying a compressive forceto set the adhesive. In such embodiments, plastic divider panels may bepositioned between respective crane mats 100 to act as a separator toensure that the adhesive does not unintentionally bond adjacent cranemats 100 together.

Turning again to FIGS. 4A-4B, dimensional lumber is loaded into orreceived by system 400 at Step 410 of system 400. One or more surfacesof the lumber are planed by a planer apparatus at Step 412 of system400. System 400 is configured to stack lumber at Step 414 according tosize for later retrieval. At Step 416, system 400 loads a compositesheet for a carrier apparatus of system 400, after which lumber isloaded side-by-side for a bottom panel of a crane mat at Step 418.

System 400 may be configured to apply glue to a top surface of thebottom panel in a manner that minimizes adhesive material cost, whichmay otherwise be a significant expense in the construction of a cranemat. In some embodiments, the panel is moved or conveyed under astationary glue dispensing apparatus while glue is dispensed from theglue dispensing apparatus onto the panel. In other embodiments, thepanel is held stationary while the glue dispensing apparatus traversesover the panel and dispenses glue onto the panel. In some embodiments, acontinuous (or in some embodiments a discontinuous) ribbon of glue isapplied along the perimeter of a given panel while a solid or a stitchedpattern of rows of adhesive is applied to the interior, central area ofthe top surface of the panel. In one embodiment, system 400 includesstationary adhesive nozzles (or other glue dispensing apparatus)positioned in a row transverse to the longitudinal orientation of thepanel. As the panel is conveyed longitudinally by a conveyer, system 400at Step 420 applies a solid glue line along the lateral and longitudinalperimeter of the top surface of the bottom panel while system 400 atStep 422 simultaneously applies a solid and/or a stitched orintermittent glue line along the central area of the top surface of thebottom panel. If a stitched or intermittent glue line is applied, theinterval between glue dots or dashes in the central area is dependent onthe speed at which the panel is conveyed under the nozzles as well asthe pulse duration of the dispensing of glue from the nozzles. Inanother embodiment, system 400 includes traversing adhesive nozzles (orother glue dispensing apparatus) positioned in a row transverse to thelongitudinal orientation of the panel. As the adhesive nozzles traverseover the stationary panel, system 400 at Step 420 applies a solid glueline along the lateral and longitudinal perimeter of the top surface ofthe bottom panel while system 400 at Step 422 simultaneously applies asolid and/or a stitched or intermittent glue line along the central areaof the top surface of the bottom panel. If a stitched or intermittentglue line is applied, the interval between glue dots or dashes in thecentral area is dependent on the speed at which the adhesive nozzlestraverse over the panel as well as the pulse duration of the dispensingof glue from the nozzles.

At Step 424, the same glue application technique is performed by system400 to the next succeeding panel, which will be oriented transverse tothe bottom panel, and which is stacked upon the bottom panel. The load,stacking, and gluing process of Steps 418, 420, 422, and 424 is repeatedat Steps 426 and 428 for the additional panels that will be stacked toform the desired crane mat. An assembled plurality of laminated,composite panels of a crane mat are then stacked on top of an additionalplurality of composite panels of separate crane mats at Steps 430, 432,434, and 436 and all are pressed in a press system of system 400 at Step438. In some embodiments, 3 or 4 sets of crane mats may be pressed atone time in this way. In other embodiments, a greater or fewer number ofcrane mats may be pressed at the same time.

At Steps 440, 442, and 444 the composite panels are removed from thepress system of system 400 and separated from one another. At Step 446,the composite panels of a particular crane mat are cut by one or morecutting machines of system 400 to a desired finished length and width.At Step 448, the various edges of the crane mat may optionally bebeveled by system 400. For various embodiments of crane mats, at Step450 one or more routers or plunge cutters of system 400 are configuredto cut optional grooves 301, 311 discussed above on either or both ofthe top or bottom surfaces of the crane mat. For various embodiments ofcrane mats, at Step 452 one or more routers or plunge cutters of system400 are configured to cut optional grooves 201 on either or both of thetop or bottom surfaces of the crane mat. At Step 454, system 400 isconfigured to optionally paint or seal one or more sides of the cranemat. At Step 456, the completed crane mat having the desiredconfiguration is moved to inventory.

Turning to FIGS. 5A1-5A8, there is shown another embodiment of a methodof making a crane mat of the present disclosure comprising an apparatusor system 500. It should be understood that other types of vehicle orground protection mats, including access mats, can be manufactured bysystem 500 using the method disclosed herein. In various embodiments,one or more aspects of system 500 can be merged with one another,omitted, or made part of additional apparatuses or system components.These systems may be configured to fabricate a crane mat billet, whichmay be further cut or trimmed to meet customer specifications. Cranemats comprising any number of layers may be manufactured using themethods disclosed herein. In one embodiment, system 500 is configured toproduce a 5-layer crane mat with hardwood top and bottom layers andsoftwood intermediate layers. In one embodiment, a 5-layer crane mat,such as crane mat 100, includes 8 ft long hardwood lumber members on thetop and bottom layers, 8 ft long southern yellow pine (or othersoftwood) for the middle layer, and either 16 ft or 18 ft long southernyellow pine (or other softwood) for the two intermediate layerspositioned on opposite sides of the middle layer and adjacent torespective hardwood layers. As mentioned above and as discussed below,an 8 ft×16 ft or 16 ft 5-layer crane mat 100 may be sawed in half toobtain two 4 ft×16 ft or 18 ft 5-layer crane mats 100. System 500 may beused to manufacture 3-layer mats. In one embodiment, a 3-layer matmanufactured by system 500 includes 14 ft long southern yellow pine (orother softwood) lumber members on the top and bottom layers and 8 ftlong southern yellow pine (or other softwood) for the middle layer. Insome embodiments, a 3-layer mat is configured to omit some of the lumbermembers in the bottom layer to help fixate the mat in place on theground during use and to reduce or eliminate unintended hydroplaningthat may otherwise occur in wet fields.

As shown in the figures, to optimize the production of crane mats,system 500 may have multiple, continuous feed, planer lines, asidentified by “planer 1” and “planer 2”. In this embodiment, dimensionallumber is loaded into or by system 500 at Step 510 of system 500. Thedimensional lumber may be softwood for one or more middle layers of thecrane mat or hardwood for one or more outer layers of the crane mat. Asshown in FIG. 5A-1, to manufacture an intermediate layer for either a 4ft×16 ft 5-layer crane mat or a 4 ft×18 ft 5-layer crane mat,dimensional softwood lumber, such as southern yellow pine, that is 16 ftlong or 18 ft long (depending on the desired width of the mat) is loadedinto or received by system 500 at Step 510 of system 500. The softwoodmay have previously been kiln dried to Southern Pine Inspection Bureau(SPIB) specifications for moisture content to range from approximately14% to approximately 19%, which lies within the range for use with theadhesive disclosed herein. At Steps 512 and 514, the lumber is fed via achain feed mechanism toward an unscrammbler, which orderly orientslumber for entry into the planer. At Step 516, individual pieces oflumber are positioned side-by-side against a fence on the distal ends ofthe boards to cause the distal end of each board to be relatively evenwith one another. At Steps 518, 520 and 522, the lumber ispinched/grabbed in approximately 24 inch wide groups for conveying toone of two planers. In other words, if 2×8 lumber is being used, thenapprox. 3 boards may be pinched/conveyed to each of the two planers. If2×10 lumber is being used, then approx. 2 boards may be pinched/conveyedto each of the two planers.

At Steps 524 and 526, the lumber is conveyed through the planers andprimers and planed and primed on at least two sides, for example, thetop and bottom faces. At Steps 528, 530, and 532, the planed and primedlumber is dropped onto a chain deck and conveyed to an unscrammbler. AtStep 534, individual pieces of lumber are positioned side-by-sideagainst a fence on the distal ends of the boards to cause the distal endof each board to be relatively even with one another. At Step 536, thelumber members are pinched together side to side to create an 8 ft widelumber segment or layer, which is even-ended again at Step 538. Thislumber segment or layer is transferred and trimmed at Steps 540 and 542by crosscutting the longitudinal ends of the boards to obtain a desiredlength for this lumber segment or layer. Both longitudinal ends of theboards may be sawn to obtain the desired length. At Steps 544, 544, 548,and 550, the trimmed lumber segment or layer is conveyed to a stack forwork in process (WIP) storage.

As shown in FIGS. 5A-2 and 5A-5, Steps 510 through 550 are repeated fordimensional softwood lumber, such as southern yellow pine, that is 8 ftlong for purposes of manufacturing the middle, transverse layer ofeither a 16 ft wide 5-layer crane mat or an 18 ft 5-layer crane mat. Inaddition, as shown in FIGS. 5A-3 and 5A-6, Steps 510 through 550 arerepeated for dimensional hardwood lumber that is 8 ft long for purposesof manufacturing the top and bottom layers of either a 16 ft wide5-layer crane mat or an 18 ft 5-layer crane mat. In this way, respectivesoftwood and hardwood lumber segments may be inventoried to match thetiming and consumption requirements for assembling 5-layer crane mats ofthe instant disclosure. In some embodiments, at least approximately54,000 linear feet of lumber per hour may be planed, primed and stackedin WIP storage.

Turning to FIG. 5A-4, at Step 560 a, either a a 16 ft or a 18 ft longsoftwood lumber segment or layer is pulled from WIP storage and loadedonto an in-feed roller on a portion of the manufacturing line that isdesignated to receive lumber segments having any of these lengths.Similarly, at Step 560 b, an 8 ft long softwood lumber segment is pulledfrom WIP storage and loaded onto in-feed chains on a portion of themanufacturing line that is designated to receive an 8 ft softwood lumbersegment. Similarly, at Step 560 c, an 8 ft long hardwood lumber segmentis pulled from WIP storage and loaded onto in-feed chains on a portionof the manufacturing line that is designated to receive an 8 ft hardwoodlumber segment.

At Step 562 a, 562 b, 562 c, lumber segments are vacuum lifted ontoeither a roller conveyor (14 ft, 16 ft, or 18 ft long softwood lumbersegments) or a belt conveyor (8 ft long softwood and hardwood lumbersegments) configured to receive the respective lumber segments. Forhardwood lumber segments, at Steps 564, 566, and 568 (see FIG. 5A-6),the conveyor conveys the hardwood lumber segments for final dimensionaladjustment and entry into a flash dry oven for adjusting the moisturecontent of the hardwood lumber to a desired range. The flash dry ovenallows for the use of hardwood that is not kiln dried. In someembodiments, hardwood lumber segments are heated in the flash dry ovento reduce the moisture content at the surface of the hardwood lumbersegments, from over 30% before heating to approximately 7% toapproximately 30% after heating, to ensure desired adhesion ofrespective adjacent lumber segments by an adhesive when positionedtherebetween.

At Step 570 a, 570 b, 570 c, the softwood and hardwood lumber segmentsare conveyed by the respective conveyors to a composition gantry forassembly of the desired crane mat configuration. For hardwood lumberconveyed from the flash dry oven to the composition gantry, moisturecontent is verified, via one or more sensors, to lie within desiredparameters before assembly.

Assembly of a plurality of 5-layer crane mats, for example, begins atStep 572 (see FIG. 5A-7) by vacuum lifting and positioning a plasticdivider panel on a glue composition belt conveyor table. The gluecomposition belt conveyor table is configured to automatically indexvertically downward to receive successive lumber or plastic dividerpanels. The plastic divider panel may be made from high densitypolyethylene (HDPE) and be configured to be approximately 0.50 inchthick. The plastic divider panel may be sized to slightly exceed theplan form size of the crane mat being manufactured to allow sensors todetect the existence and position of the plastic divider panels. Theadhesive described below has been found to resist sticking to the HDPEdivider panel, which allows the divider panel to act as a barrier to theadhesive when separating multiple assembled stacks of crane matsfollowing the clamping process described below. At Step 574, after theglue composition belt conveyor table has been indexed downwardly, afirst, bottom layer comprising hardwood lumber is then vacuum lifted andpositioned on top of the plastic divider panel. At Step 576, a layer ofadhesive is applied to desired portions on top of the first, bottomlayer of hardwood lumber.

At Step 578 (FIG. 5A-4), after the glue composition belt conveyor tablehas been indexed downwardly, a first, intermediate layer comprisingsoftwood, such as southern yellow pine, that is either 16 ft or 18 ftlong, for example, is then vacuum lifted and positioned on top of thefirst, bottom layer. At Step 580, a layer of adhesive is applied todesired portions on top of the first, intermediate layer of softwoodlumber.

At Step 582 (FIG. 5A-7), after the glue composition belt conveyor tablehas been indexed downwardly, a middle intermediate layer comprisingsoftwood, such as southern yellow pine, that is 8 ft long is then vacuumlifted and positioned on top of the first, intermediate layer ofsoftwood lumber. At Step 584 (FIG. 5A-7), a layer of adhesive is appliedto desired portions on top of the middle intermediate layer of softwoodlumber.

At Step 586, after the glue composition belt conveyor table has beenindexed downwardly, a second, intermediate layer comprising softwood,such as southern yellow pine, that is either 16 ft or 18 ft long, forexample, is then vacuum lifted and positioned on top of the middleintermediate layer. At Step 588, a layer of adhesive is applied todesired portions on top of the second, intermediate layer of softwoodlumber.

At Step 590, after the glue composition belt conveyor table has beenindexed downwardly, a last, top layer comprising hardwood lumber is thenvacuum lifted and positioned on top the second, intermediate layer ofsoftwood lumber. At Step 592, after the glue composition belt conveyortable has been indexed downwardly, a plastic divider panel is vacuumlifted and positioned on top of the last, top layer comprising hardwoodlumber. As shown at Step 594, the process of stacking and applyingadhesive (ref. Steps 574 through 592) is repeated a total of 5 times.When manufacturing 3-layer mats using system 500, the process ofstacking may be repeated a total of 8 times to match the capacity of thepresses.

At Step 596, the assembled stack of 5-layer crane mats is transferred toone of three clamping presses, and at Step 598, the stack is pressed andheld in compression for approximately 25 minutes or to a desired time toallow the adhesive to set a desired amount. In this embodiment, thethree presses are connected to one another and are configured tolaterally traverse and index into position so that an available one ofthe presses receives the assembled stack from the conveyor. The use ofthree presses allows for matching the assembly of respective stacks ofcrane mats with the “open time” and with the clamp time of the adhesive.

For purposes of this disclosure, a suitable adhesive is PurbondHB-E102/UR5151 from Henkel Adhesives Corp. This adhesive provides for an“open time” of 10 minutes before the adhesive skins over and beforewhich the assembled stack must be clamped to provide a proper bond.After a stack of crane mats have been assembled, within the 10 minuteopen time an available one of the three presses traverses laterally intoa position to receive the assembled stack. The press then compresses thestack for approximately 25 minutes. While the adhesive in that assembledstack is curing, another assembled stack is being made by system 500.Within the 10 minute open time for the adhesive, another one of thethree presses traverses laterally into a position to receive the nextassembled stack. The press then compresses the stack for approximately25 minutes. The process occurs again for a third assembled stack. Aftera fourth assembled stack of crane mats has been assembled, the adhesivehas been cured to a desired state in the first assembled stack. Thefirst assembled stack leaves the first press just in time for the firstpress to receive the fourth assembled stack. A continuous stream ofcrane mats may be manufactured in this way. In some embodiments, a totalof five 5-layer crane mats 100, together with plastic divider panelspositioned therebetween, may be assembled and stacked on top of oneanother before 9 minutes and 30 seconds elapses. This allows for atleast approximately 30 seconds to transfer the assembled stack to one ofthe available presses and to initiate the compressive force on the stackbefore the 10 minute “open time” of the adhesive is exceeded.

The clamping presses are further configured to adjust the clamping loadaccording to the size of the assembled stack. For example, if a stack of14 ft 3-layer mats is received by the press, a computer control systemis configured to engage a hydraulic cylinder to apply a predeterminedcompressive load to the assembled stack. By contrast, if a stack of 16ft 5-layer crane mats is received by the press, the computer controlsystem is configured to engage a hydraulic cylinder (and possibly adifferent hydraulic cylinder if the press is equipped with multiplecylinders) to apply a different predetermined compressive load to theassembled stack.

At Step 600, a pressed crane mat stack is conveyed from one of thepresses to a de-stacker scissor lift that is configured to automaticallyindex vertically upward, whereupon a de-stacker arm at Step 602 sweeps aplastic divider panel onto a return chain circuit to convey the plasticdivider panel at Step 604 back to the composition gantry. At Step 606,after the de-stacker scissor lift has been indexed updwardly, a pressed5-layer crane mat is moved by the de-stacker arm to the trim and chamfercircuit for final processing. As shown at Step 608, the de-stackingprocess repeats 5 times (or for as many times as there are pressed cranemats and plastic divider panels to de-stack).

At Steps 610, 612, and 614, each of the pressed, 5-layer crane mats isconveyed to a cross-cut and trim station whereupon the 5-layer crane matis even-ended, trimmed to a finished length, and chamfered alongperipheral edges. At Steps 616, and 618, each of the pressed, 5-layercrane mats is conveyed to a lineal cut and trim station whereupon the5-layer crane mat is ripped along the centerline to divide the 8 ft×16ft or 18 ft billet to become two, 4 ft×16 ft or 18 ft crane mats.Additional chamfering of the peripheral edges is completed at this step.The ripping and chamfering in this embodiment are performed by saws thatare fixed in position while the crane mats are conveyed past the saws ina pre-programmed fashion.

At Steps 620, 622, and 624, the fully sawn and trimmed 5-layer cranemats are conveyed and transferred via a vacuum lifter to out-feedrollers and stacked until 5 crane mats have been accumulated. At Step626, the stack of 5 crane mats are gravity fed to an out-feed bump. AtSteps 628 and 630, the 5 crane mats are transferred to a paint booth andpainted on all 4 exposed sides and ends to protect the end grain of theboards from absorbing moisture. A suitable protectant is Anchorseal®from UC-Coatings, LLC. At Step 532, the sealed set of 5 crane mats maybe transferred to inventory for sale. Crane mats 100 made using thesystems and methods disclosed herein allow for the bonding together ofdissimilar lumber materials, such as hardwood and softwood, and in acontinuous stream of production.

One or more aspects of systems 400 and 500 are operable by one or morecomputers and/or one or more programmable logic controllers (PLC's). Thecomputers and/or PLC's may be coupled with one or more sensorsconfigured for reporting position, measurements, status, and other dataregarding elements of systems 400 and 500 and the crane mats beingfabricated, and motors, actuators and the like for controlling theoperation of one or more aspects of systems 400 and 500. The computersand/or PLC's may be connected to one another and to other computers ordevices via a wired or wireless network. These devices may be connectedto one or more remote computers and/or web servers via a wired orwireless connection to the Internet.

The computers and one or more PLC's include a processor, such as acentral processing unit (CPU), for executing software, particularlysoftware stored in memory or on any computer readable medium, for use byor in connection with any computer related system or method.

A computer readable medium includes any electronic, magnetic, optical,or other physical device or apparatus that can contain or store acomputer program for use by or in connection with a computer relatedsystem or method. Memory can include any one or a combination ofvolatile memory elements (e.g., random access memory (RAM, such as DRAM,SRAM, SDRAM, etc.)) and nonvolatile memory elements (e.g., ROM, harddrive, tape, CDROM, etc.). Moreover, memory may incorporate electronic,magnetic, optical, and/or other types of storage media. Memory can havea distributed architecture where various components are situated remotefrom one another, but are still accessed by a processor.

The software may include one or more separate programs comprisingordered listings of executable instructions for implementing logicalfunctions. The software stored in memory or on any computer readablemedium may include one or more computer programs, each includingexecutable instructions executed by the processor. An operating systemmay control the execution of other computer programs and can providescheduling, input-output control, file and data management, memorymanagement, and communication control and related services.

In one embodiment, the PLC may include a computer processor such as acentral processing unit (CPU), memory, operating software stored inmemory, and various input and output (I/O) devices or data paths. TheI/O devices may include input devices, such as a keyboard, mouse, touchscreen, and/or any other user interface. The I/O devices may alsoinclude output devices, such as a computer display, a modem, a router,serial and parallel wired and wireless communication components and anyother elements needed to connect to, for example, another computer ordevice via a local network or the Internet whether wired or wirelessly.The I/O devices may further include any element or device in a feedbackcontrol system for controlling the operation and performance of anyaspect of systems 400 and 500.

While specific embodiments have been described in detail, it will beappreciated by those skilled in the art that various modifications andalternatives to those details could be developed in light of the overallteachings of the disclosure. Accordingly, the disclosure herein is meantto be illustrative only and not limiting as to its scope and should begiven the full breadth of the appended claims and any equivalentsthereof.

What is claimed is:
 1. A method of making a crane mat comprising alength that is longer than a width, comprising: (a) vacuum lifting andpositioning on an automatically vertically indexing table a first panelto receive a plurality of panels thereon, the first panel comprising aplurality of first lumber members positioned side-by-side, each of theplurality of first lumber members being oriented in a first directionthat is parallel to the width; (b) dispensing an adhesive on a topsurface of the first panel; (c) vertically positioning the indexingtable to receive a second panel; (d) vacuum lifting and positioning thesecond panel on the top surface of the first panel, the second panelcomprising a plurality of second lumber members positioned side-by-side,each of the plurality of second lumber members being oriented in asecond direction that is parallel to the length; (f) dispensing anadhesive on a top surface of the second panel; (g) verticallypositioning the indexing table to receive a third panel; (h) vacuumlifting and positioning the third panel on the top surface of the secondpanel, the third panel comprising a plurality of third lumber memberspositioned side-by-side, each of the plurality of third lumber membersbeing oriented in the first direction; (i) dispensing an adhesive on atop surface of the third panel; (j) vertically positioning the indexingtable to receive a fourth panel; (k) vacuum lifting and positioning thefourth panel on the top surface of the third panel, the fourth panelcomprising a plurality of fourth lumber members positioned side-by-side,each of the plurality of fourth lumber members being oriented in thesecond direction; (l) dispensing an adhesive on a top surface of thefourth panel; (m) vertically positioning the indexing table to receive afifth panel; (n) vacuum lifting and positioning the fifth panel on thetop surface of the fourth panel, the fifth panel comprising a pluralityof fifth lumber members positioned side-by-side, each of the pluralityof fifth lumber members being oriented in the first direction; (o)applying a compressive force to the first, second, third, fourth andfifth panels as a unit until the adhesive is set; and (p) cutting theunit to desired peripheral dimensions.
 2. The method of claim 1,including the step of vacuum lifting and positioning a divider panel onthe indexing table before step (a).
 3. The method of claim 2, includingthe step of vacuum lifting and positioning a divider panel on theindexing table after step (n).
 4. The method of claim 3, includingrepeating steps (a) through (o) at least four times to form a stack ofat least five units, wherein each of the units is separated by a dividerpanel, and applying the compressive force to the stack of at least fiveunits until the adhesive is set.
 5. The method of claim 4, including thestep of de-stacking the units before cutting.
 6. The method of claim 1,wherein the step of applying the compressive force to the unit includesapplying pressure for approximately 25 minutes.
 7. The method of claim1, wherein the first and the fifth panels comprise hardwood lumber andthe second, the third, and the fourth panels comprise softwood lumber.8. The method of claim 1, including the step of planing a top and abottom face of each of the first, the second, the third, the fourth, andthe fifth lumber members before initiating step (a).
 9. The method ofclaim 1, including the step of forming the first panel, the secondpanel, the third panel, the fourth panel, and the fifth panel bypositioning the respective plurality of first, second, third, fourth,and fifth lumber members side-by-side.
 10. A high speed manufacturingsystem for making a crane mat, comprising: a layer assembler thatpositions lumber members horizontally side-by-side to form a lumberlayer of a desired peripheral size; a robotic assembler comprising (a) avacuum lifter to lift and position the lumber layer onto an indexertable, wherein the indexer table automatically adjusts a height of thetable to receive the lumber layer and a plurality of next lumber layerspositioned in sequence vertically thereon and transverse to one another,and (b) an adhesive dispenser to dispense adhesive across each lumberlayer; a press to compress at least five lumber layers together as anassembled unit to bond the layers by the adhesive; and a plurality ofsaws to cut the bonded layers to a finished size.
 11. The system ofclaim 10, wherein the lumber members in respective top and bottom panelscomprise a hardwood species, and wherein the lumber members in each ofthe panels positioned between the top and bottom panels comprise asoftwood species.
 12. The system of claim 10, wherein the press is oneof a plurality of laterally movable presses configured to receive theunit from the robotic assembler.
 13. The system of claim 10, including aconveyor to continuously convey lumber.
 14. The system of claim 13,including a planer connected to the conveyor to plane the lumber priorto forming the lumber layer.
 15. The system of claim 14, including aprimer connected to the conveyor to prime the lumber after planing butprior to forming the lumber layer.
 16. The system of claim 15, includinga computer controller comprising a computer processor, a computerreadable medium accessible by the processor, and software stored on thecomputer readable medium for executing the step of controlling theconveyor, the planer, the primer, the robotic assembler, the adhesivedispenser, the press, and the saws.
 17. The system of claim 10, whereinthe press is configured to apply a compressive force simultaneously toat least 5 assembled units mounted on top of one another.
 18. The systemof claim 10, including a layer trimmer configured to trim each of aplurality of longitudinal ends of the lumber members positionedside-by-side to adjust a length of the lumber members to form the lumberlayer.
 19. A method of making a crane mat, comprising: positioning aplurality of lumber members side by side to form a plurality of panels;positioning a plurality of panels on one another in alternatingtransverse directions with respect to one another, wherein the pluralityof lumber members in a top panel and a bottom panel are oriented in atransverse direction, wherein the plurality of lumber members in atleast one panel positioned between the top panel and the bottom panel isoriented in a longitudinal direction; and bonding each of the panels toan adjacent one of the panels with an adhesive.
 20. The crane mat ofclaim 19, wherein the plurality of lumber members in the top and bottompanels comprise a hardwood species, and wherein the plurality of lumbermembers in the panels positioned between the top and bottom panelscomprises a softwood species.